I have used a galvanizing compound called Galvalite made by a company called ZRC Worldwide (
http://www.zrcworldwide.com/) and had great results. I used it on all the galvanized parts including the liner on a CS64 restoration. No rust at all so far. looks like the day I coated it.
Before I bought it I asked them how it compared to Rustoleum Cold Galvanizing, the guy laughed and said 'it doesn't".
Its not cheap but I like to do things right, one time.